Process for preparing parfried potato strips having an extended hold time upon finish frying

ABSTRACT

Potato strips, which are cut from raw potatoes and blanched, are contacted with an aqueous solution containing one or more hydrocolloids to deposit a hydrocolloid layer on the surface of the strips. The potato strips preferably are partially dried before being contacted with an aqueous starch-based slurry to provide a starch-based batter coating over the hydrocolloid layer. The potato strips having the dual coating of a hydrocolloid and a batter are then parfried and frozen. When reconstituted by finish frying in hot oil, the resulting french fries have an extended holding quality, remaining crisp and tender for prolonged periods after finish frying.

BACKGROUND OF THE INVENTION

This invention relates to the preparation of partially fried, frozenpotato strips which have extended holding quality after finish frying.More particularly, the invention relates to the preparation of frozen,par fried potato strips which exhibit a crisp but tender exteriorsurface for extended periods of time after finish frying

Control of the textural properties of french fries after finish fryingis of great concern to operators of fast food restaurants. Typically,french fries served by fast food restaurants are prepared by finishfrying frozen partially fried (i.e., parfried) potato strips in fat oroil. Desirably such parfried and frozen potato strips, after finishfrying, exhibit a crisp and tender exterior surface and a fluffy, mealyinner core. However, parfried potato strips presently available sufferfrom the disadvantage that when finish fried for consumption, they losetheir desired crispness within a relatively short period of time andtend to become limp and soggy. This change in texture is due to themigration of internal moisture within the fried strips into the outersurface of the potato strips. Such migration of moisture is acceleratedby holding the potato strips, after finish frying, under a heat lamp, apractice commonly used by fast food operators to maintain the frenchfries at desired serving temperature.

A number of procedures have been proposed heretofore for extending theholding time of french fries, so that the french fries remain crisp andtender for extended periods of time after finish frying, even when heldunder a heat lamp. For example, U.S. Pat. No. 3,597,227 disclosescoating the surface of potato strips with an aqueous dispersion of ahigh amylose starch prior to deep frying to improve the crispness offinish fried potato strips. U.S. Pat. No. 5,141,759 discloses thatpotato strips having increased crispness and extended holding time afterfinish frying are produced by coating the strips, prior to parfrying,with an aqueous starch slurry containing chemically modifiedungelatinized potato starch, chemically modified ungelatinized cornstarch and rice flour. U.S. Pat. No. 5,302,410 discloses providingblanched potato strips with a "glaze" coating of an aqueous solutionhaving a pH 5.5-8.5 and containing hydrolyzed starch having a DE of lessthan 12, to provide parfries which retain crispness for an extendedperiod after finish frying. U.S. Pat. No. 5,431,944 discloses theproduction of french fries having a crispy texture by coating blanchedpotato strips with a batter mix containing a leavening agent, a blend ofstarch and high amylose starch, dextrin and a food gum. U.S. Pat. No.5,622,741 discloses that potato strips having an extended hold timeafter finish frying are produced by coating blanched potato strips withan aqueous slurry containing corn flour, corn starch and low solubilitydextrin.

Some of these prior art procedures have been more effective than othersin providing potato strips which retain desired textural characteristicsfor an extended period after finish frying. However, all of these priorprocedures suffer from disadvantages which limit their acceptability tofast food restaurant operators. For example, batter coatings usedheretofore, even those designated as thin-coat batters, have arelatively high solids content and deposit a relatively thick battercoating on the surface of the potato strips. Although the batter coatedstrips have a crisp texture after finish frying, they develop anundesirable degree of toughness and chewiness during holding. Moreover,the batter coating detracts from the natural potato flavor of theproduct and forms a discernible coating layer on the surface of thefrench fries to detract from the natural appearance of the finish friedpotato strips. The use of batter coatings having a low solids contenthas not been feasible since such low solids content batters have reducedadherence to the surface of the potato strips and tend to dissociatefrom the potato strips during parfrying and/or finish frying. While the"glaze" coating on potato strips disclosed in the '410 patent iseffective in extending crispness of french fries after finish fryingwithout the development of toughness and chewiness, such "glaze"coatings are not as crisp as batter coated french fries.

SUMMARY OF THE INVENTION

The present invention provides parfried potato strips which retain acrisp, tender surface texture and a fluffy mealy inner core, withoutbecoming tough and chewy, for extended periods of time after finishfrying. Parfried potato strips having such textural characteristics areprepared by providing blanched potato strips with a dual coating priorto parfrying, that is, an initial glaze coating of an aqueoushydrocolloid solution, followed by a subsequent coating of an aqueousbatter slurry, with the batter slurry preferably having a relatively lowsolids content.

In accordance with this invention, raw potatoes are washed, cut intostrips of a desired size and blanched in accordance with well knownprocedures, such as those disclosed in U.S. Pat. No. 4,254,153 to Rosset al. After blanching, the potato strips are contacted with an aqueoussolution of one or more hydrocolloids, such as natural or modified foodgums, gelatin, pectins, starches, modified starches, high amylosestarches, dextrins, maltodextrins, and the like. The pH of thehydrocolloid solution is maintained at a level in the range of 5.0 to8.5 by any suitable means, such as the addition of an edible basic salt,preferably tetrasodium pyrophosphate (TSPP), to the hydrocolloidsolution. Conventional ingredients, including a sequestering agent suchas sodium acid pyrophosphate (SAPP), a reducing sugar such as dextrose,a flavor enhancer such as sodium chloride, and a leavening agent, may,if desired also be included in the aqueous hydrocolloid solution.Preferably, the hydrocolloid-coated potato strips are heated to reducethe internal moisture of the strips and to set the hydrocolloid coatingon the surface of the strips. The potato strips are then coated with anaqueous starch-based batter with the batter typically being applied byeither immersing the potato strips in the starch-based slurry, orspraying the slurry onto the surface of the potato strips. The battercoated strips are drained to remove excess batter coating, and thebatter coated potato strips are parfried and frozen in accordance withknown procedures.

The aqueous starch slurry used in the present invention may have arelatively low solids content, which may be substantially lower thanconventional starch-based batters even the so-called thin-coat battercoatings. For example, product having the desired characteristics ofthis invention may be produced using a starch-based batter having asolids content as low as about 5%. The use of such a low solids contentbatter results in a reduced level of batter solids on the potato strips.Due to the presence of the initial hydrocolloid coating, a starch basedbatter slurry having such a relatively low solids levels can be used andstill provide parfried potato strips having a crisp, tender surfacelayer for prolonged periods of time after finish frying. Moreover, withthe initial hydrocolloid layer, a batter coating having a relatively lowsolids level can be used without separating from the potato stripsduring parfrying, finish frying or handling.

The french fries prepared by finish frying the parfried potato strips ofthis invention have a superior texture and color and are characterizedby a crisp surface layer and mealy interior. The french fries remaincrisp and tender for prolonged periods after finish frying withoutdeveloping the toughness and chewiness typically exhibited byconventional batter coated french fries upon holding.

DETAILED DESCRIPTION OF THE INVENTION

Raw potatoes, preferably of the Russet-Burbank variety, are washed andsorted to remove defective potatoes, and are then optionally peeled. Ifa finished product with peel remaining is desired, the peeling step isomitted. The whole potatoes are optionally preheated for about 20-40minutes at a temperature between about 110° F. to 150° F. (43° C. to 65°C.) and are then cut into strips of desired size and shape customarilyused for french fries, such as shoestring potato strips, crinkle cutstrips, and straight cut strips, which may range from about 0.25 inch(6.35 mm) to about 0.5 inch (12.7 mm) square in cross-section, or intolarger cuts. After cutting, the strips may be washed to remove surfacestarch. The potato strips are then blanched according to conventionalprocedures to inactivate enzymes, gelatinize the starch and removeexcess free sugars which might cause uncontrolled browning. Typicallythe strips are blanched by immersion in hot water at about 160° F.-210°F. (71° C.-99° C.,) for 2-15 minutes, with a temperature of 170° F.-190°F. (76°-88° C.,) for 4-10 minutes being preferred. Alternatively, thepotato strips may be blanched in steam at atmospheric pressure for about2-10 minutes.

After blanching, the potato strips are contacted with an aqueoussolution containing one or more hydrocolloids, with the hydrocolloidsolution having a pH in the range of about 5.0 to 8.5, preferably from6.5 to 7.5. Contacting the potato strips with the hydrocolloid solutionhaving a pH in this range, such as by spraying, dipping, immersion, andthe like, forms a thin hydrocolloid coating or glaze on the surface ofthe potato strips which not only promotes increased crispness of thepotato strips on finish frying, but also promotes improved adhesion ofthe subsequently applied batter layer, even batter coatings having arelatively low level of solids. That is, the hydrocolloid coatingprovides the potato strips with a surface which enables the subsequentbatter coating to more firmly adhere, particularly batter coatingshaving a relatively slow solids concentration.

Suitable hydrocolloids which may be used include food gums, gelatin,pectins, starches, modified starches, high amylose starches, dextrins,maltodextrins, and the like. Suitable food gums which may be usedinclude methyl cellulose, guar gum, xanthan gum, gum arabic,carrageenan, locust bean gum, and similar food gums, and mixturesthereof. When a food gum is used as the hydrocolloid, it is present inan amount of from about 0.05% to 1.0% by weight of the aqueous solution.When hydrocolloids other than a food gum are used, they are used at aconcentration in the aqueous solution of from about 0.5% to 12.0% byweight, preferably between 2% and 6% by weight of the aqueous solution.Hydrolyzed starch products, such as dextrins and maltodextrins having aDextrose Equivalent (DE) value of less than about 12, are preferred foruse as the hydrocolloid in coating the potato strips. Suitablemaltodextrins include potato maltodextrins and corn maltodextrins.

The pH of the aqueous hydrocolloid solution is maintained in the rangeof between 5.0 and 8.5, preferably between 6.5 and 7.5, by the additionof a basic alkali salt to the solution. Tetrasodium pyrophosphate (TSPP)is generally preferred, but any basic alkali salt which is suitable foruse in food products in the amount required to adjust the pH of theaqueous solution to the desired range may be used. Maintaining the pH ofthe hydrocolloid solution within this range has been found to enhancethe crisp, tender characteristics of the potato strips after subsequentbatter coating and finish frying.

If desired, a conventional food-grade sequestering agent, such as sodiumacid pyrophosphate (SAPP) may be included in the aqueous hydrocolloidsolution, in order to minimize product discoloration. If SAPP is used,it is usually present in amounts of about 0.2% to 1.0% by weight. Theaqueous solution may also contain from 0.1 % to about 1.0% by weight ofa reducing sugar, such as dextrose, to facilitate uniform colordevelopment during frying. Other conventional materials may also beincluded in the aqueous solution, such as, for example, salt or otherflavor enhancers, leavening agents, and the like.

The aqueous hydrocolloid solution is maintained at a temperature ofbetween about 130° F. to 180° F. (54° C. to 71° C.) when contacted withthe blanched potato strips. The blanched strips are contacted with theaqueous hydrocolloid solution by immersing the strips in a dip tankcontaining the solution for a period of time sufficient to coat thestrips with hydrocolloid, typically from about 10 to 60 seconds. Otherprocedures may, of course, be used, such as contacting the strips withthe aqueous solution in a flume or tube, spraying the solution onto thestrips, and the like.

Following the application of the hydrocolloid solution, thehydrocolloid-coated potato strips preferably are heated undertime-temperature conditions sufficient to partially dry the potatostrips, that is, to accomplish a moisture loss of up to about 25% fromthe strips and to set the hydrocolloid coating on the surface of thepotato strips. The level of moisture loss will, of course, depend to alarge extent on the size cut of the potato strips. For shoestring cuts,a moisture loss in the range of from 12% to 16% is desirable. Suitableproduct may be produced without drying the hydrocolloid-coated strips.If the potato strips are dried, they are preferably subjected to heatedair, in a conventional hot air drier, at a temperature of from about130° F. to 350° F. (54° C. -177° C.) for from 5 to 40 minutes.

The potato strips, having a hydrocolloid layer on the surface of thestrips, are then coated with an aqueous starch slurry, by contacting thestrips, such as by dipping, immersion or spraying, with an aqueousstarch-based batter to form a starch coating or batter coating over thehydrocolloid layer on the strips. Excellent results are obtained with astarch-based slurry having a solids content as low as about 5% byweight. Starch-based slurries having a higher solids content, up to 50%or more may, of course be used. However, as the solids concentration inthe starch slurry is increased, particularly as it increases above about30% by weight, french fries produced from the coated strips become lesstender and more chewy than those produced using a lower solids contentstarch slurry. Preferably, the potato strips pick up between about 8 to14 percent of their weight in starch slurry.

The starch slurry may contain one or more starches and flours typicallyused in the batter coating of potato strips, including, for example,corn flour, wheat flour, rice flour, dextrin, starch, modified foodstarch such as modified potato starch, modified corn starch, and thelike. In addition, the slurry may also contain minor amounts of otheringredients, such as whey, sodium chloride, a leavening agent (typicallya carbonate salt and a leavening acid such as sodium acidpyrophosphate), and a food gum. For example, whey can be included topromote the development of golden brown color upon frying. Food gumsprovide viscosity control and help maintain the solids in suspension inthe slurry, particularly when slurries having a relatively low solidscontent are used. Suitable dry starch blends which have been found to beparticularly effective are obtained from Bunge Foods Corporation,Bradley, Ill. under the designations LS-C and Clear Choice Type A. Thedry batter blend LS-C has been identified by the supplier as modifiedfood starch, rice flour, salt, leavening (sodium acid pyrophosphate andsodium bicarbonate), cornstarch, xanthan gum, beta carotene and whey. Asidentified by the supplier, the composition of dry batter blend ClearChoice Type

A is modified food starch, tapioca dextrin, salt, corn starch, leavening(sodium acid pyrophosphate and sodium bicarbonate), whey and xanthangum.

The batter coating slurry is prepared by blending the dry ingredients,typically, one or more starches, modified or unmodified, and flours, anddextrin, and other optional ingredients such as whey, leavening, salt,and flavorings, and then adding the dry blend, with agitation, to theamount of ambient temperature water necessary to give a slurry havingthe desired solids content. The starch slurry is maintained at atemperature between about 40° F. to 75° F. (4.4° C. to 24° C.),preferably between 60° F. to 70° F. (15.6° C. -21.0° C.) while theslurry is mixed and during coating.

Typically, conventional starch-based batter slurries used in priorcoating procedures for french fries have a relatively high solids level,on the order of 40% or more. The use of batter coatings having arelatively low solids content has not been considered feasible due topoor adhesion of the batter coating to the potato substrate, with theresult that the batter coating tends to "blow off" or separate from thesubstrate upon par frying or finish frying of the potato strips. Inaccordance with the present invention, however, the batter coatingexhibits excellent adhesion to the potato strip substrate even when theaqueous starch slurry has a low solids content, that is on the order ofabout 5% by weight. The initial hydrocolloid coating on the surface ofthe blanched strips provides a surface for increased adherence of thesubsequent starch coating, even when the starch slurry has a relativelylow solids level. Batter pick-up on the potato strips is reduced due tothe use of the starch slurry having a reduced solids content, with theresult that the resulting potato strips, after parfrying and finishfrying, have less tendency to develop tough, chewy characteristics uponholding.

The aqueous starch slurry may be applied by any suitable means, such asby dipping, spraying or immersion. After coating with the starch slurry,excess starch slurry is removed from the potato strips by draining thestrips or by brief use of an air knife.

The potato strips are then parfried in oil at a temperature of about325° F. to 390° F. (162° C. to 199° C.) for a short period of time,about 20 to 90 seconds. The par-fried strips are frozen, packaged andstored for subsequent use. To prepare the parfried strips forconsumption, they are finish fried in deep fat or oil bath at atemperature of about 300° F. to 375° F. (149° C. to 190° C.) for 1.5 to3.5 minutes to develop color and crispness. The resulting potato stripsare light golden brown in color, and have a crisp, tender surface and apuffy mealy inner core upon finish frying. Such finish fried potatostrips produced in accordance with this invention, retain their crisp,tender outer layer over extended periods of time under a heat lamp,without developing an undesirable tough, chewy characteristic, commonwith conventional batter-coated french fries.

The following examples are intended to illustrate, but not to limit, thepresent invention. Unless otherwise indicated, all parts and percentagesare by weight.

EXAMPLE I

A series of tests was run to demonstrate the effect of the presentinvention on the textural characteristics of french fries held under aheat lamp over an extended period of time. To provide a basis forcomparison, four tests were run- Each of these four tests utilizedpotato strips obtained from Russet Burbank potatoes which had beensteam-peeled, heated for from 28 to 34 minutes at a temperature in therange of from 117° F. to 126° F., cut into strips about 0.3 inches (0.8cm.) in cross-section, and water blanched for 6.5 minutes at 180° F.

In Test 1A the potato strips were processed into parfried strips usingconventional procedure, with the strips having no hydrocolloid coatingor starch-based batter coating. That is, the blanched potato strips wereimmersed for 40 seconds in an aqueous solution containing 0.5 percent byweight sodium acid pyrophosphate (SAPP) and 0.3 percent by weightdextrose. The solution was maintained at 160° F. After removal from thesolution, the strips were dried in a conventional drier at 148° F. for asufficient period of time to effect a weight loss of 17.5%. The driedstrips were then parfried for 50 seconds at 370° F., precooled withambient air, and frozen.

In Test 1B. the potato strips were processed into par fries having abatter coating but no hydrocolloid coating. That is, the blanched stripswere processed following the procedure used in Test 1A, with theexception that the blanched strips were immersed in an aqueous solutioncontaining 0.8 percent tetrasodium pyrophosphate (TSPP), 0.4 percentsodium acid pyrophosphate and 0.2 percent dextrose, with the aqueoussolution having a pH in the range of between 5.0 and 8.5, and thestrips, after drying, were coated with an aqueous starch slurry. Toprovide the coating, the dried strips were immersed in an aqueousstarch-based slurry, which was prepared by mixing dry batter blend LS-C,supplied by Bunge Foods Corporation, Bradley, Ill., with sufficientwater (65° F.) to provide a slurry having a solids content of 30%. LS-Cbatter contains modified food starch, rice flour, salt, leavening(sodium acid pyrophosphate and sodium bicarbonate),cornstarch, xanthangum, beta carotene and whey. The batter coated strips were drained toremove excess slurry, parfried for 50 seconds at 370° F., precooled withambient air and frozen.

In Test 1C, the potato strips were processed into par fries having ahydrocolloid coating on the surface of the strips but no batter coating.That is, the blanched strips were processed following the procedure usedin Test 1A, with the single exception that the strips were immersed for40 seconds in an aqueous hydrocolloid solution (160° F.) having a pH inthe range of 5.0 to 8.5 containing 7.0 percent by weight potatomaltodextrin, 0.8 percent by weight tetrasodium pyrophosphate (TSPP),0.4 percent by weight sodium acid pyrophosphate (SAPP), and 0.2 percentby weight dextrose. After immersion, the strips were dried, par fried,cooled and frozen in accordance with the procedure described for Test1A.

In Test 1D, the potato were processed in accordance with the presentinvention, with the potato strips having both an initial hydrocolloidcoating and a subsequent starch-based batter coating. That is, theblanched potato strips were immersed for 40 seconds in an aqueoushydrocolloid solution containing 1.0 percent by weight potatomaltodextrin, 0.8 percent by weight tetrasodium pyrophosphate, 0.4percent by weight sodium acid pyrophosphate, and 0.2 percent by weightdextrose. The strips were then dried at 148° F. for a sufficient time toeffect a weight loss of 17.5%, and the dried strips were immersed in anaqueous starch-based slurry, which was prepared by mixing dry batterblend LS-C, supplied by Bunge Foods Corporation, Bradley, Ill., withsufficient water (65° F.) to provide a slurry having a solids content of10%. The batter-coated strips were then drained, par fried for 50seconds at 375° F., precooked with ambient air and frozen.

Frozen samples of products of each of the four tests described abovewere prepared for evaluation by finish frying 1.5 pounds of each testproduct in hot oil for 2.5 minutes at 350° F. and holding the finishfried potato strips under a heat lamp at about 160° F. before evaluatingthe strips for texture. Samples of each Test product were evaluated by asensory panel at 4 minutes, 10 minutes and 20 minutes after finishfrying. In evaluating the quality of french fries, crispness andtenderness, although difficult to quantify, are importantcharacteristics. A lack of crispness typically identifies a productwhich is tough and chewy. Crispness and tenderness in french fries arecharacteristics which indicate the ability of the product tosufficiently resist the initial bite but then disappear with a quickmeltaway in the mouth. If the potato strip does not readily break downduring subsequent mastication, it is considered to have undesirabletough and chewy characteristics. The results of this evaluation are setout below.

Initially, upon removal from the finish fryer, all test samples weregolden brown in color, with a crisp and tender outer surface. It shouldbe noted that commercially-available batters such as the LS-C batterused in this series of tests are intended to be used at a solids levelof 30% or more, and do not adhere well to a food substrate when appliedat low concentrations. However, in the present Test 1D, the batteradhered well to the potato strips, even though a batter concentration of10% was used.

AFTER 4 MINUTE HOLD

Test 1A samples (no hydrocolloid coating, no batter coating) weremoderately crisp and tender, and were slightly limp with some softcenters.

Test 1B samples (no hydrocolloid coating, batter coating only) were verycrisp but slightly hard; some separation of batter coating from thestrips.

Test 1C samples (only hydrocolloid coating, no batter) were moderatelycrisp and tender.

Test 1D samples (hydrocolloid coating and batter coating) were verycrisp and tender.

AFTER 10 MINUTE HOLD

Test 1A samples were slightly crisp and tender, and had becomemoderately limp.

Test 1B samples were crisp and tender but the separation of battercoating from the strips was more pronounced.

Test 1C samples were moderately crisp and tender, but becoming slightlylimp.

Test 1D samples were crisp and tender with very slight amount oflimpness beginning to develop.

AFTER 20 MINUTE HOLD

Test 1A samples were not crisp, but very limp and soggy.

Test 1B samples were slightly crisp and tender, slightly limp; battercoating separation evident.

Test 1C samples were slightly crisp and tender, with slight to moderatelimpness.

Test 1D samples were crisp and tender with a few slightly limp strips.

The results of these tests clearly establish that the present inventionresults in the production of french fries that stay crisp and tender forextended periods of time after finish frying. French fries that had bothan initial hydrocolloid coating and a subsequent batter coating werecrisper and retained a crisp and tender characteristic longer thancorresponding french fries that has neither coating or only one coating.

EXAMPLE II

A series of tests was run to show the effect of different hydrocolloidsin the present invention. In carrying out these tests, the potatoes wereprocessed in a manner similar to that in Example I, that is, RussetBurbank potatoes were steam peeled, heated for 34 minutes at 117° F.,cut into strips 0.30 inches in crossection, water blanched for 6.5minutes at 180° F. and immersed in an aqueous hydrocolloid solutionhaving a pH in the range of 5.0 to 8.5 for 40 seconds at 160° F. In allof the tests the hydrocolloid solution contained 0.8% TSPP, 0.4% SAPPand 0.2% dextrose, with the following hydrocolloids being included inthe solution:

    ______________________________________    Test 2A      5.0% Potato maltodextrin (DE of 6)    Test 2B      1.0% High amylose corn starch    Test 2C      0.5% Corn maltodextrin (DE of 10)    Test 2D      0.5% Tapioca starch    Test 2E      0.3% Methylcellulose gum    ______________________________________

After removal from the solution, the strips were dried in a conventionaldrier at 148° F. for a sufficient period of time to effect a weight lossof 17.5%. After drying, the potato strips for each test were immersed inan aqueous starch slurry, which was prepared by mixing dry batter blendLS-C, supplied by Bunge Foods Corporation, Bradley, Ill., withsufficient water (65° F.) to provide a slurry having a solids content of30%. The batter coated strips were drained to remove excess slurry,parfried for 50 seconds at 370° F., precooled with ambient air andfrozen.

Frozen samples of products of each of the four tests described abovewere prepared for evaluation by finish frying 1.5 pounds of each testproduct in hot oil for 2.5 minutes at 350° F. and holding the finishfried potato strips under a heat lamp at about 160° F. before evaluatingthe strips for texture. Samples of each Test product were evaluated by asensory panel at 10 minutes after finish frying. The results of thisevaluation are set out below.

    ______________________________________    Sample   Evaluation Results    ______________________________________    2A       Very crisp and tender, not tough or chewy    2B       Very crisp and tender, not chewy    2C       Crisp and tender; did not become chewy over time    2D       Crisp and tender; did not become chewy over time    2E       Quite crisp with some excessive browning    ______________________________________

As shown by these test results, all of the hydrocolloids used in thistest were effective in producing french fries which had extended holdingqualifies and remained crisp and tender for extended periods afterfinish frying.

EXAMPLE III

A series of tests was run to show the effect of varying theconcentration of the starch-based batter, both with and without aninitial hydrocolloid coating, on the holding quality of par fried potatostrips after finish frying. That is, potato strips, having an initialhydrocolloid coating were contacted with aqueous starch slurries havinga solids content of 20%, 30% and 40%, and these tests were then repeatedwith the exception that the potato strips did not have a hydrocolloidcoating when contacted with the starch slurries.

Each of these tests utilized potato strips which had been water blanchedfor 7 minutes at 180° F. and immersed in an aqueous solution for 40 sec.at 160° F. In tests 3A, 3B and 3C the aqueous solution contained 6.0%potato maltodextrin (DE 6), 0.5% SAPP and 0.2% dextrose. In tests 3D, 3Eand 3F, the aqueous solution contained 0.5% SAPP and 0.2% dextrose, butno potato maltodextrin or other hydrocolloid. After immersion in theaqueous solution the potato strips were dried in heated air for a periodof time sufficient to reduce the weight of the strips by about 18%. Thestrips were then sprayed with an aqueous starch slurry, formed usingBatter Mix 963-5179, supplied by Griffith Laboratories, Alsip, Ill.,which contained modified food starch, rice flour, corn starch, dextrinpotato starch, leavening, wheat starch, whey, partially hydrogenatedsoybean oil and flavoring, with sufficient water to provide an aqueousstarch slurry having the desired solids content. In these tests, thesolids concentration of the slurry was varied from 20% to 40%. Theconditions used are set out below, with viscosity being determined usinga Stein cup.

    ______________________________________                     Batter Solids                                Viscosity                                        Batter Pick-Up    Test  Hydrocolloid                     (%)        (sec.)  (%)    ______________________________________    3A    6.0%       20%        6.4     10.1    3B    6.0%       30%        6.5     10.8    3C    6.0%       40%        7.4     12.1    3D    0.0%       20%        6.4     7.6    3E    0.0%       30%        6.5     5.0    3F    0.0%       40%        7.4     6.3    ______________________________________

The batter coated strips were drained, par fried for 45 seconds at 370°F. air cooled and frozen. Frozen samples of products of each of thetests described above were prepared for evaluation by finish frying 1.5pounds of each test product in hot oil for 2.5 minutes at 350° F. andholding the finish fried potato strips under a heat lamp at about 160*F.before evaluating the strips for texture. Samples of each Test productwere evaluated by a sensory panel at 10 minutes after finish frying. Theresults of this evaluation are set out below.

    ______________________________________    Test Hydrocolloid (%)                     Batter Solids (%)                                 Evaluation    ______________________________________    3A   6.0         20          crisp and tender    3B   6.0         30          crisp and slightly chewy    3C   6.0         40          crisp and moderately chewy    3D   0.0         20          less crisp and more chewy                                 than 3A    3E   0.0         30          less crisp and more chewy                                 than 3B    3F   0.0         40          less crisp and more chewy                                 than 3C    ______________________________________

As shown in these tests, french fries produced using batter coatingshaving a solids content of up to 40%, when applied after an initialhydrocolloid coating, exhibit desired crispness after extended periodsafter finish frying. However, the french fries become more chewy as thebatter concentration increases from 20% to 40%. All samples producedusing no hydrocolloid layer before the batter coating were inferior tothe samples produced using both an initial hydrocolloid layer and abatter layer.

While the present invention has been described by reference to specificembodiments, it will be apparent to those skilled in the art that otheralternative embodiments or modifications may be employed withoutdeparting from the scope of this invention.

What is claimed is:
 1. A process for producing frozen parfried potatostrips which remain crisp and tender for an extended time after finishfrying which comprisescutting raw potatoes into strips, blanching thepotato strips, contacting the blanched potato strips with an aqueoushydrocolloid solution having a pH in the range of between 5.0 and 8.5 toform a hydrocolloid coating on the surface of the strips, contacting thehydrocolloid-coated potato strips with an aqueous starch-based slurry,to form a starch-based batter coating over the hydrocolloid coatingparfrying the twice coated potato strips, and freezing the parfriedstrips.
 2. The process defined in claim 1 in which thehydrocolloid-coated potato strips are heated to partially dry the stripsand set the hydrocolloid coating on the surface of the strips.
 3. Theprocess defined in claim 2 in which the blanched potato strips arecontacted with an aqueous solution containing about 0.5% to 12% byweight of a hydrocolloid selected from the group consisting of gelatin,pectins, starches, modified starches, high amylose starches, dextrins,maltodextrins, and combinations thereof.
 4. The process defined in claim3 in which the blanched potato strips are immersed in an aqueoussolution containing from 2% to 6% by weight of a hydrolyzed starchproduct having a DE value of from 2 to
 10. 5. The process defined inclaim 2 in which the blanched potato strips are contacted with anaqueous solution containing about 0.05% to 1.0% by weight of a food gum.6. The process defined in claim 2 in which the hydrocolloid coatedpotato strips are heated to effect a moisture loss of up to about 25% byweight of the strips.
 7. The process defined in claim 6 in which thepotato strips are subjected to heated air having a temperature of from130 F. to 350 F. for from 5 to 40 minutes.
 8. The process defined inclaim 1 in which the aqueous starch-based slurry has a solids content of5% by weight or more.
 9. The process defined in claim 8 in which thesolids content of the starch slurry is from 5% to 50%.
 10. The processdefined in claim 8 in which the potato strips are coated with the starchslurry by dipping or immersing the potato strips in an aqueousstarch-based slurry having a temperature of between about 40 F. to 75 F.